Measures of mortality

1. No. Biostat - 5
Date: 10.08.2008
MEASURES OF MORTALITY
Lecture Series on Lecture Series on
BiostatisticsBiostatistics
Dr. Bijaya Bhusan Nanda, Dr. Bijaya Bhusan Nanda,
M. Sc (Gold Medalist) Ph. D. (Stat.)M. Sc (Gold Medalist) Ph. D. (Stat.)
Topper Orissa Statistics & Economics Services, 1988Topper Orissa Statistics & Economics Services, 1988
[email protected]@yahoo.com

2. CONTENTSCONTENTS

IntroductionIntroduction

Determinants of MortalityDeterminants of Mortality

Uses of Mortality dataUses of Mortality data

Sources of Mortality dataSources of Mortality data

Measures of MortalityMeasures of Mortality

Life TableLife Table

3. LEARNING OBJECTIVELEARNING OBJECTIVE

They will be able to compute They will be able to compute
different indices of mortality.different indices of mortality.

They will be able to spell out general They will be able to spell out general
determinants of mortality.determinants of mortality.

They will be able to spell out They will be able to spell out
usefulness of mortality indicators.usefulness of mortality indicators.

4. Death:Death:
““the permanent disappearance of all evidences of the permanent disappearance of all evidences of
life at any time after birth” (WHO).life at any time after birth” (WHO).
•MortalityMortality: :
•A demographic event – Average risk of dying of a A demographic event – Average risk of dying of a
person in the group during a time span. person in the group during a time span.
•This is one of the three determinants of This is one of the three determinants of
population change i.e. fertility, mortality and population change i.e. fertility, mortality and
migrationmigration..
• Factors of mortality patternsFactors of mortality patterns::
•Endogenetics (biological):Endogenetics (biological):
•Exogenetic(environmental):Exogenetic(environmental):
INTRODUCTION

5. 
VVary over Space and Timeary over Space and Time
DETERMINANTS OF MORTALITY
Classified in to three categories:
Demographic structure- Age, Sex Composition etc.
Social advancement- Age at marriage, Adequacy of
medical facilities, General condition of nutrition,
Housing and Sanitation, Literacy, Religion, Caste
and Community beliefs etc.
Economic development- Occupation, Standard of
living/ per capita income , Type of economy etc.

6. Useful for projecting the future size of the
population
Identify population groups that are at high risk
and in need of health service
Indicatives of quality of life and expectation of
life at birth.
Useful guides to planners
Helpful to insurance companies
USES OF MORTALITY RATE

7. There are two sources:There are two sources:
I.I. Direct sourceDirect source
 Registration of vital eventsRegistration of vital events
Sample Registration SurveysSample Registration Surveys
National Family Health SurveysNational Family Health Surveys
I.I. Indirect sourceIndirect source
Age data of two consecutive censuses may be Age data of two consecutive censuses may be
used to estimates death ratesused to estimates death rates
Demographic year book: U.N. PublicationDemographic year book: U.N. Publication
World Health Organization (WHO) also World Health Organization (WHO) also
provides dataprovides data
SOURCES OF MORTALITY DATA

8. MEASURES OF MORTALITYMEASURES OF MORTALITY
 It is the quantitative and statistical devices It is the quantitative and statistical devices
to label the risk of mortality to which a to label the risk of mortality to which a
population is exposed over a period of time.population is exposed over a period of time.
Different measures of mortality:-Different measures of mortality:-
 Crude death rate:Crude death rate:
Crude death rate (d) =( D/P)*1000Crude death rate (d) =( D/P)*1000
D= No. of deaths in a population during a D= No. of deaths in a population during a
given calendar yeargiven calendar year
P= average number of persons living in the P= average number of persons living in the
population during the yearpopulation during the year

9. 
MeritsMerits
 requires minimum data on mortalityrequires minimum data on mortality
Easy to interpretEasy to interpret

DemeritsDemerits
 Since the risk of death is not uniform Since the risk of death is not uniform
for different segments of population for different segments of population
(age, sex etc.) CDR is a crude measure (age, sex etc.) CDR is a crude measure
and cant be used directly for comparing and cant be used directly for comparing
the levels of mortality in two or more the levels of mortality in two or more
countries.countries.

10. Age specific death rate (ASDR)Age specific death rate (ASDR)
nnDD
xx = No. of death between x and x+n in the yr. = No. of death between x and x+n in the yr.
nnPP
xx = No. of persons aged between x and x+n in = No. of persons aged between x and x+n in
the middle of yr.the middle of yr.
Note: LNote: Line graph of ASDR at y-axis and age at ine graph of ASDR at y-axis and age at
x-axis it shows J-shape pattern for developed x-axis it shows J-shape pattern for developed
countries and U-shape pattern for developing countries and U-shape pattern for developing
countries because in developing countries countries because in developing countries
mortality rates are comparatively higher at mortality rates are comparatively higher at
younger ages.younger ages.
Age Specific Death Rates(ASDR)
n
D
x
n
P
x
´1000==
nnMM
xx
==

11. No. of infants dying under one year of age in a No. of infants dying under one year of age in a
year per thousand live birth in a given year per thousand live birth in a given
geographical region.geographical region.
DD
0 0 : No. of infants who died before celebrating : No. of infants who died before celebrating
their first birthday.their first birthday.
B : Total No. live births occurring in that year B : Total No. live births occurring in that year
and geographical region.and geographical region.
Infant Mortality Rate (IMR)
D
0
B
´1000IMR=IMR=

12. Defined as the total number of deaths of Defined as the total number of deaths of
children aged 1 to 4 yrs. per 1000 population children aged 1 to 4 yrs. per 1000 population
of the same age in a given year and of the same age in a given year and
geographical region.geographical region.
Child Mortality Rate (CMR)
CDR =
No. of deaths of children aged 1to
4 yr in given yr and region
tot. population aged 1 to 4 in
the given yr and a given region
×1000

13. No. of infants dying within the first 4 weeks or up No. of infants dying within the first 4 weeks or up
to 28 days of life per 1000 live birth in a year and to 28 days of life per 1000 live birth in a year and
geographical region.geographical region.
NMR =
Deaths of infants up to 4 weeks
No. of live births
× 1000
No. of infant deaths during the first seven days of No. of infant deaths during the first seven days of
life per 1000 live births in a year and geographical life per 1000 live births in a year and geographical
region.region.
ENMR =
Deaths of infants in the first week of life
No. of live births
×1000
Neonatal Mortality Rate (NMR):
Early Neonatal Mortality Rate (NMR):

14. No. of still births/ late foetal deaths (after 28 No. of still births/ late foetal deaths (after 28
weeks of gestation) plus deaths within first weeks of gestation) plus deaths within first
week of life in a year and geographical region week of life in a year and geographical region
for 1000 births (live and still) in a year and for 1000 births (live and still) in a year and
region.region.
Perinatal Mortality Rate (PMR)
PMR=
Foetal deaths after 28weeks of gestation +
deaths of newborns within 7days
No. of live births during the same year
×1000

15. Number of infants deaths after 28 days to Number of infants deaths after 28 days to
less than 1yr (between 4 weeks to 52 weeks) less than 1yr (between 4 weeks to 52 weeks)
of age per 1000 live births in a given year.of age per 1000 live births in a given year.

Post Neonatal Mortality Rate (PNMR)
PNMR=
No. of deaths of newborns between
4weeks or less than 1yr old in a year
No. of live births during the same yr
×1000

16. Maternal Mortality Ratio (MMR)
No. of deaths of women while pregnant or No. of deaths of women while pregnant or
within 42 days of termination of pregnancy within 42 days of termination of pregnancy
from any cause related to pregnancy/ from any cause related to pregnancy/
childbearing and child birth per 100,000 live childbearing and child birth per 100,000 live
births in a given year.births in a given year.
No. of live births during the same year
× 100000MMR=
Deaths of pregnant women and women
after termination of pregnancy within 6
weeks from any cause related to
pregnancy

17. Maternal Mortality Rate (MMRT)
MMRT =

No. of maternal deaths of
women in age 15-49
× 1000
Number of maternal deaths while pregnant Number of maternal deaths while pregnant
or within 42 days of termination of or within 42 days of termination of
pregnancy from any cause related to pregnancy from any cause related to
pregnancy/ childbearing and childbirth per pregnancy/ childbearing and childbirth per
100,000 women in reproductive ages 15-49.100,000 women in reproductive ages 15-49.
No. of women in age 15-49
in a given yr

18. 
Foetal Death:Foetal Death:
Deaths prior to the complete expulsion or Deaths prior to the complete expulsion or
extraction from its mother of a product of extraction from its mother of a product of
conception at any time of pregnancy.conception at any time of pregnancy.

Still BirthStill Birth
Death of foetus after completing 28 weeks and Death of foetus after completing 28 weeks and
till the time of birth.till the time of birth.

Incidence RateIncidence Rate
Number of NEW cases of specified diseases Number of NEW cases of specified diseases
occurring in a defined population during a occurring in a defined population during a
specified period of time.specified period of time.

19. ((Continued…………)Continued…………)
Prevalence RatePrevalence Rate
Number of all current cases (old and new) of a Number of all current cases (old and new) of a
disease at one point in time in relation to defined disease at one point in time in relation to defined
population.population.

Incidence rate =
No. of new cases of specified
disease during a given period
Population at risk
×1000
No. of new and old cases
of specified disease existing
at a given point in time
Prevalence rate =
Estimated population at
the same point in time
×1000

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Neonatal
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Late
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Infant Death
Child Death (<5 Years)
Time Reference for Mortality in Childhood and Infancy

21. 
The risk in a population may vary The risk in a population may vary
largely with various socio-economic largely with various socio-economic
and biological traits.and biological traits.

The lack of reliable and requisite data The lack of reliable and requisite data
presents serious problem sometimes of presents serious problem sometimes of
considerable magnitudeconsiderable magnitude..
Limitations of Measures of Mortality

22. Exercise: Calculate the crude and Age specific death Exercise: Calculate the crude and Age specific death
rates of the population from the following data rates of the population from the following data
Age-group Age-group
(Years)(Years)
PopulationPopulation DeathsDeaths
Under 10Under 10 20,00020,000 600600
10-2010-20 12,00012,000 240240
20-4020-40 50,00050,000 1,2501,250
40-6040-60 30,00030,000 1,0501,050
Above 60Above 60 10,00010,000 500500

23. Expectation of LifeExpectation of Life
The curate Expectation of life, (eThe curate Expectation of life, (e
xx) gives the ) gives the
average number of completed years of life lived average number of completed years of life lived
by the cohort by the cohort ll
00 after age x by each of after age x by each of lx lx
persons attaining that age. The complete persons attaining that age. The complete
expectation of life, denoted as eexpectation of life, denoted as e
xx
oo
,,

measures the measures the
average number of years a person of given age average number of years a person of given age
can be expected to live under the prevailing can be expected to live under the prevailing
mortality conditions. It gives the number of mortality conditions. It gives the number of
years of life entirely completed and includes years of life entirely completed and includes
the fraction of the year survived in the year in the fraction of the year survived in the year in
which death occur, which on the average can which death occur, which on the average can
be taken to be ½ years. ebe taken to be ½ years. e
xx
o = o =
ee
x x +1/2+1/2

24. REFERENCEREFERENCE

An Introduction to the Study of An Introduction to the Study of
Population, Bhaskar D. MishraPopulation, Bhaskar D. Mishra

Techniques of demographic Analysis, Techniques of demographic Analysis,
K. B Pathak, F. RamK. B Pathak, F. Ram

Fundamentals of Applied Statistics, Fundamentals of Applied Statistics,
S.C Gupta and V. K Kapoor.S.C Gupta and V. K Kapoor.

25. THANK YOU